E-Book, Englisch, Band Volume 124, 248 Seiten
Reihe: Advances in Agronomy
E-Book, Englisch, Band Volume 124, 248 Seiten
Reihe: Advances in Agronomy
ISBN: 978-0-12-800360-2
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)
Autoren/Hrsg.
Weitere Infos & Material
1;Front Cover;1
2;Advances in Agronomy;4
3;Copyright;5
4;Contents;6
5;Contributors;8
6;Preface;10
7;Chapter One: Opportunities and Challenges of Soil Carbon Sequestration by Conservation Agriculture in China;12
7.1;1. Introduction;14
7.2;2. CA in China;17
7.2.1;2.1. CT systems in different agroeco regions;17
7.2.2;2.2. Challenges to adopting CA in China;22
7.2.2.1;2.2.1. Diverse cropping systems;22
7.2.2.2;2.2.2. Low yield under some CA technologies;23
7.2.2.3;2.2.3. Suitable small-size seeders for small farm holdings;23
7.2.2.4;2.2.4. Understanding and perceptions of CA;24
7.3;3. Effects of CA in China;24
7.3.1;3.1. Soil bulk density;24
7.3.2;3.2. Soil water and temperature regimes;26
7.3.3;3.3. Crop yields;28
7.3.4;3.4. Soil organic carbon;29
7.3.5;3.5. SOC stock;32
7.3.6;3.6. SOC sequestration and soil quality;35
7.3.7;3.7. Limitations of SOC research under CA;36
7.3.7.1;3.7.1. Research topics;36
7.3.7.2;3.7.2. Soil C study method;37
7.4;4. Potential and Opportunities for CA and SOC Research;38
7.4.1;4.1. Intensive farming problems;38
7.4.2;4.2. Soil erosion control;39
7.4.3;4.3. Residue management;39
7.4.4;4.4. Rural development and economic profit;39
7.4.5;4.5. Labor shortage;41
7.5;5. Conclusions;41
7.6;Acknowledgments;42
7.7;References;42
8;Chapter Two: A Meta-Analysis and Review of Plant-Growth Response to Humic Substances: Practical Implications for Agriculture;48
8.1;1. Introduction;49
8.2;2. Meta-Analysis;52
8.2.1;2.1. Methods;52
8.2.1.1;2.1.1. Literature search and refinement;52
8.2.1.2;2.1.2. Response and moderator (explanatory) variables;52
8.2.1.2.1;2.1.2.1. Environmental conditions;53
8.2.1.2.2;2.1.2.2. Plant type;53
8.2.1.2.3;2.1.2.3. HS properties;53
8.2.1.2.4;2.1.2.4. Method of application;54
8.2.1.3;2.1.3. Statistical analyses;54
8.2.2;2.2. Results;56
8.2.2.1;2.2.1. Data quality and aggregate effect of HS on plant growth;56
8.2.2.2;2.2.2. Factors influencing HS efficacy;57
8.2.2.3;2.2.3. Factor interactions;59
8.3;3. Plant-Growth Response to HS: Moderating Factors;62
8.3.1;3.1. General plant-growth response;62
8.3.2;3.2. Application rate;63
8.3.3;3.3. HS properties;65
8.3.4;3.4. Environmental conditions;66
8.3.5;3.5. Plant type;67
8.4;4. Practical Use of HS in Agriculture;68
8.4.1;4.1. Direct application;68
8.4.2;4.2. Application as synergists;70
8.5;5. Knowledge Gaps and Research Needs;73
8.6;6. Conclusions;74
8.7;Acknowledgments;74
8.8;Appendix A. Study References for SDW Data used in the Meta-Analysis;75
8.9;Appendix B. Study References for RDW Data used in the Meta-Analysis;88
8.10;References;96
9;Chapter Three: Properties and Management of Acid Sulfate Soils in Southeast Asia for Sustainable Cultivation of Rice, Oil ...;102
9.1;1. Introduction;103
9.1.1;1.1. Definition of acid sulfate soil;104
9.1.1.1;1.1.1. Sulfidic materials;104
9.1.1.2;1.1.2. Sulfuric horizon;104
9.1.2;1.2. Classification;105
9.1.3;1.3. Distribution;106
9.1.4;1.4. Management;107
9.2;2. Formation and Properties of Acid Sulfate Soils in Southeast Asia;108
9.2.1;2.1. Formation of pyrite;108
9.2.2;2.2. Oxidation of pyrite;111
9.2.3;2.3. Formation of jarosite;114
9.2.4;2.4. Biological properties of acid sulfate soils;115
9.3;3. Management of Acid Sulfate Soils for Rice Cultivation;117
9.3.1;3.1. Al and/or Fe toxicity;117
9.3.2;3.2. Soil management;123
9.4;4. Management of Acid Sulfate Soil for Oil Palm Cultivation;128
9.4.1;4.1. Al toxicity in oil palm;129
9.4.2;4.2. Soil management;135
9.5;5. Management of Acid Sulfate Soil for Cocoa Cultivation;138
9.5.1;5.1. Al toxicity;138
9.5.2;5.2. Soil management;145
9.6;6. Summary and Conclusions;146
9.7;Acknowledgment;147
9.8;References;147
10;Chapter Four: Plant Responses to Limited Moisture and Phosphorus Availability: A Meta-Analysis;154
10.1;1. Introduction;155
10.2;2. Complexity and Limitations of the Current Literature;156
10.3;3. Dry Soil Restricts P Movement and P Uptake by Plants;170
10.4;4. Effects of Moisture and P Limitation on Shoot Processes;173
10.4.1;4.1. Growth;173
10.4.2;4.2. Water-use efficiency;175
10.4.3;4.3. Leaf water relations;175
10.4.4;4.4. Biochemical processes;178
10.4.5;4.5. P resorption (P remobilization);179
10.5;5. Effects of Moisture and P Limitation on Root Processes;180
10.6;6. Effects of Moisture and P Limitation on Soil P Dynamics;182
10.7;7. Influence of Arbuscular Mycorrhizal Fungi;186
10.7.1;7.1. Effect of AMF on plant P uptake under drought;189
10.7.2;7.2. Effect of AMF on plant growth under drought;192
10.7.3;7.3. Effect of AMF on plant water relations under drought;193
10.7.4;7.4. Effect of AMF on plant biochemical processes under drought;196
10.8;8. Hydraulic Redistribution;198
10.9;9. Limitations of Laboratory Studies;199
10.10;10. Concluding Remarks;200
10.11;Acknowledgments;201
10.12;References;201
11;Chapter Five: Elicitation: An Underutilized Tool in the Development of Medicinal Plants as a Source of Therapeutic Seconda ...;212
11.1;1. Introduction;213
11.1.1;1.1. Background;213
11.1.2;1.2. Genetic variation;213
11.1.3;1.3. Environmental variation;214
11.1.4;1.4. Medicinal plants response to stress;215
11.1.5;1.5. Elicitation;216
11.2;2. Classification of Elicitors;217
11.2.1;2.1. Biotic elicitors;217
11.2.2;2.2. Abiotic elicitors;219
11.2.2.1;2.2.1. Hormonal elicitors;219
11.2.2.1.1;2.2.1.1. Jasmonic acid;219
11.2.2.1.2;2.2.1.2. Salicylic acid;220
11.2.2.1.3;2.2.1.3. Other hormones;220
11.2.2.1.4;2.2.1.4. Brassinosteroids;221
11.2.2.1.5;2.2.1.5. Abcisic acid;221
11.2.2.1.6;2.2.1.6. Auxins;221
11.2.2.2;2.2.2. Inorganic chemical elicitors;221
11.2.2.2.1;2.2.2.1. Heavy metals;221
11.2.2.2.2;2.2.2.2. Effects of nutrient deficiencies and toxic metals on secretion of root exudates;222
11.2.2.3;2.2.3. Physical elicitors;223
11.2.2.3.1;2.2.3.1. UV-B radiation;223
11.2.2.3.2;2.2.3.2. Salinity;224
11.2.2.3.3;2.2.3.3. Drought stress;225
11.2.2.3.4;2.2.3.4. Thermal stress;225
11.3;3. Elicitation in Whole Medicinal Plants;226
11.4;4. Role of Elicitation in Agricultural Development of Medicinal Plants;227
11.5;5. Currently Utilized Elicitors;229
11.6;6. Conclusion;230
11.7;References;230
12;Index;242
Chapter Two A Meta-Analysis and Review of Plant-Growth Response to Humic Substances
Practical Implications for Agriculture
Michael T. Rose *,†; Antonio F. Patti *; Karen R. Little *,†,‡; Alicia L. Brown †; W. Roy Jackson *; Timothy R. Cavagnaro †,§ * School of Chemistry, Monash University, Clayton, Victoria, Australia
† School of Biological Sciences, Monash University, Clayton, Victoria, Australia
‡ School of Applied Sciences and Engineering, Monash University, Churchill, Victoria, Australia
§ School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, PMB1 Glen Osmond, SA, Australia Abstract
The breakdown products of plant and animal remains, extracted in an alkaline solution, are commonly referred to as humic substances (HS). They can be extracted from a wide variety of sources, including subbituminous coals, lignites (brown coals), peat, soil, composts, and raw organic wastes. The application of HS to plants has the potential to improve plant growth, but the extent of plant-growth promotion is inconsistent and relatively unpredictable when compared to inorganic fertilizers. The goal of this review was to determine the magnitude and likelihood of plant-growth response to HS and to rank the factors contributing to positive growth promotion. These factors included the source of the HS, the environmental growing conditions, the type of plant being treated, and the manner of HS application. Literature reports of exogenously applied HS–plant interactions were collated and quantitatively analyzed using meta-analytic and regression tree techniques. Overall, random-effects meta-analysis estimated shoot dry weight increases of 22 ± 4% and root dry weight increases of 21 ± 6% in response to HS application. Nevertheless, actual responses varied considerably and were mainly influenced by the source of the HS applied, the rate of HS application, and to a lesser extent, plant type and growing conditions. HS from compost sources significantly outperformed lignite and peat-derived HS in terms of growth promotion, while HS application rate nonlinearly moderated the growth response under different circumstances. Our results demonstrate the difficulty in generalizing recommendations for the use of HS in agriculture; however, some specific suggestions for maximizing the efficacy of HS under certain conditions are offered. We also outline some recent developments in the use of HS as synergists for improving fertilizer use efficiency and the activity of microbial inoculants. Finally, we identify a number of research gaps, which, when addressed, should clarify how, when, and where HS can be best applied for the greatest benefit. Keywords Humic acid Soil amendment Crop stimulant Organic matter Soil carbon Compost Lignite Peat 1 Introduction
Humic substances (HS) are a category of naturally occurring organic compounds that arise from the decomposition and transformation of plant, animal, and microbial residues (MacCarthy, 2001). They are a natural component of practically all soils, but levels vary and there is considerable evidence that modern agriculture involving practices such as soil tillage has resulted in their decline (Novotny et al., 1999; Shepherd et al., 2001). The loss of humic material, together with overall reductions in soil organic matter, is of concern because they play important roles in maintaining key soil functions and plant productivity (Lal, 2004; Sparling et al., 2006). Consequently, there is interest in the application of HS-based amendments to agricultural systems in order to reverse this trend (Piccolo and Mbagwu, 1997; Quilty and Cattle, 2011). HS are chemically complex with no clearly defined chemical structure, although generalized models have been proposed (Bruccoleri et al., 2001). While traditionally viewed as complex macromolecules, they have more recently been described as mixtures of smaller molecules, containing aromatic rings, aliphatic chains, and ionizable functional groups that interact with each other to form aggregated colloids (Piccolo, 2001; Pinton et al., 2009; Sutton and Sposito, 2005). There is significant evidence that the exogenous application of HS can help improve soil fertility, primarily through their complex chemistry which facilitates interactions with a variety of mineral and nonmineral organic soil components. Some of the documented benefits of soil amendment with HS include improved soil aggregation and structure, increased pH buffering and cation exchange capacity, increased water retention capacity, increased bioavailability of immobile nutrients (such as P, Fe, and Zn), and decreased toxicity of aluminum and heavy metals (Chen et al., 2004a; Imbufe et al., 2005; Peiris et al., 2002; Piccolo and Mbagwu, 1989; Piccolo et al., 1997; Tan and Binger, 1986). As well as indirectly influencing plant productivity through modification of soil characteristics, HS can also directly impact on physical and metabolic plant processes. A recent review by Muscolo et al. (2013) reviews evidence for the hormone-like effects of HS and how these relate to the chemical structural features of these materials. The authors highlight a predominance of auxin-like effects and that nonlignin structures are the principal contributors. These effects can be elicited through an interaction with either roots or shoots. For example, hormonal-like responses on plant roots were demonstrated by Trevisan et al. (2010) and HS may also stimulate H+-ATPase and ion transporter activity in the root plasma membrane (Mora et al., 2010; Pinton et al., 1997, 2009). Both these effects can enhance nutrient acquisition, the former through increased soil exploration, and the latter by accelerating nutrient uptake. These effects appear to be especially prominent for cases involving HS derived from compost and vermicomposts, which may contain auxin-related compounds (Muscolo et al., 1999; Quaggiotti et al., 2004), including indole-acetic acid derivatives and other low molecular weight organic acids (Russell et al., 2006). In contrast, effects on leaf function have been less well documented and appear somewhat contradictory (Nardi et al., 2002). Foliar application of HS may increase leaf chlorophyll concentration (Sladký, 1959), but it is also recognized that HS contain a range of functional groups which are able to interfere with photosynthesis (Pflugmacher et al., 2006). Foliar applications have also been shown to influence transpiration, though the mechanism is unclear and both increases and decreases in water loss and leaf gas exchange have been observed. Despite numerous publications on the potential positive effects of HS on plant growth and productivity over more than five decades (Billingham, 2012; Chen et al., 2004b; Quilty and Cattle, 2011) and substantial interest in their potential for improving nutrient-use efficiency and contributing to C sequestration in the soil, the use of commercial products containing HS in agriculture varies and there is scepticism about their effectiveness (Billingham, 2012). Part of the reason for this is no doubt related to the wide range in physicochemical properties of HS, which vary according to the method of extraction and the environmental matrix from which they are sourced. HS are formed under a variety of environmental conditions and are, therefore, highly heterogeneous and structurally difficult to define (Senesi, 1994). Commercial products often contain mixtures of humic materials and added plant nutrients; hence, the cause of any observed beneficial effect cannot be easily attributed to the HS themselves. In addition, the recommended rates of application of commercial products are generally very small in relation to the natural levels of HS present in the soil. As a consequence, the effect of an HS product is substantially less predictable than other plant or soil amendments of a known chemical structure, such as inorganic fertilizers or synthetic organics including pesticides and growth regulators. Moreover, because of the multiple chemical functional groups of HS, a particular HS product may behave completely differently under different environmental conditions, or when applied to different plant species. Finally, as with many chemical fertilizers, the timing, location, and rate of application will play a crucial role in determining whether beneficial or harmful effects will evolve and whether or not any beneficial effects are economically worthwhile. This is particularly important because recent publications have pointed out potential negative effects and have questioned the economic viability of applying HS for improved crop production (Asli and Neumann, 2010; de Santiago et al., 2010; Hartz and Bottoms, 2010). In light of the potential benefits of HS, together with their inconsistent performance under field conditions, we sought to improve the understanding of the effects of HS on plant growth by conducting a meta-analysis of the published literature. More specifically, our objectives were (i) to quantify the magnitude and likelihood of plant-growth promotion, in terms of...
